Conservation biology is a scientific field that focuses on the preservation of biodiversity in order to protect ecosystems while meeting the needs of the human population. Humans require properly functioning ecosystems to maintain our supply of natural resources, including food, medicines, and building materials. Ecosystems also perform critical services, such as purifying our air and water. A large body of evidence indicates that such ecosystem services depend on biodiversity. Furthermore, the importance of conservation extends beyond the material needs of the current human population. Many philosophical and religious traditions argue that we bear the responsibility of preserving healthy environments for future generations of people and that non-human species have an inherent right to exist. Human activities are the primary threat to biodiversity and ecosystem health. These activities include deforestation, pollution, overharvesting of wild species, the introduction of non-native species, and global climate change caused by the burning of fossil fuels. To mitigate these threats, conservation biology combines genetics, climatology, ecology, social sciences, and many other disciplines to both identify and prevent the loss of biodiversity.